Controlling electromagnets for lifting and transporting and in apparatus therefor



June 27, 1933. K. YOUNGHUSBAND 7 CONTROLLING ELECTROMAGNETS FOR LIFTING AND TRANSPQRTING AND IN APPARATUS THEREFOR File l Aug. 11, 1928 I L 45 L JJ g w A 1 2 Z c J 2 5 m L 4' :M M WKm Patented June 27, 1933 UNITED STATES PATIENT orrl'cr.

o KENNETH YOUNGHUSBAND, 01 HAWARDEN, ENGLAND J v CONTROLLING ELEC'IBOMAGNETS FOR LIFTING AND TRANSPORTING AND IN APPARATUS THEREFOR This invention relates to controlling systems for lifting magnets and has for its primary object to increase the lifting power of such magnets over a period of working.

5 The invention consists broadly in the arrangement according to which after the lifting magnet has been subjected to a maximum energization for a predetermined period to ick up the loadthe energizing current is automatically reduced to a smaller amount suflicient to retain the load during holding and transportation.

-It will be seen that in this way the effective lifting power of the magnet is increased since, as the said maximum energization can last only for a limited period the lifting magnet becomes less heated and therefore is capable of receiving higher energiz ng currents for lifting than if the energizlng current continued without reduction during the holding and transportation as in the methods hitherto usual.

. .In order that the invention may be the 1 more clearly understood a lifting magnet controlling system in accordance therewlth Wlll now be described reference being made to the accompanying diagrammatic drawing.

Thus the numeral 1 designates the lifting magnet and the numeral 1a its energizing winding. A relay 2 is provided for controlling the degree of energization of said winding 1a, said relay'having an energizing winding 2a and normally open contacts 26 across which a resistance 3 is connected. A second relay 4 is provided for controlling the energization of said winding 2a, said relay 4 having a winding 4a and normally closed contacts 46. A one way adjustable dash pot is also associated with said relay 4 for delaying, for a time interval, the opening of said contacts 46 upon energization'of said winding 4a. The whole system is controlled by means of a master switch 5 having three fixed contacts 5a, 5b, 5c and a movable contact 5d adapted either to disengage or to simultaneously engage all three of said contacts 5a, 5b, 5c. The lines Ll, L2 represent main terminals and the circuit connections are as shown. a When the lifting magnet is to be used, the

Application filed August 11, 1928, Serial 'No. 299,074, and in Great Britain December 19; 1927. I

movable contact 5d of the master switch 5 is moved into engagement with the three fixed contacts and an energizing circuit for the winding 2a is established from line L1,

through contacts 5a, 503, 5c, 46 and said winding 2a to line L2. Contacts 26 are therefore instantly closed, thereby establishmg an energizing circuit for the winding 1a of said electromagnet from line L1 through contacts 5a, 503, 5?), said winding 1a and contacts 2b to line L2.

Thussaid winding 1a is connected directly across the mains and the electromagnet is energized sufficiently to pick up its load.

At the same time the winding 4a of the dash pct relay 4 is energized by a circuit extendmg from line L1 through contacts 5a, 5d, 50, and said Winding 4a to line L2. Therefore after a time interval depending upon the ad- ]ustment of the dash pot 40 to the contacts 47) will open thereby breaking the energizing circuit of the winding 2a. Contacts 26 thereupon open and the resistance ,3 is thrown into the energizing circuit of the winding 1a. The electromagnet is therefore less than fully energized but its degree of energization will be sufiicient to retain for transport the load which has already been attracted.

When the movable contact 5d is returned to its disengaged position the winding 1a of the magnet is de-energized so that the magnet will drop its load.- The circuit of the winding 4a isalso de-energized and as the dash pot 40 only functions in one direction the contacts 4?) will instantly close, 5 i

the whole system being therefore at the original position. What I claim and desire to secure by Letters Patent is 4 1. The combination with a lifting magnet 00 wherein all magnetic parts bear a fixed rela-- tion, of means first to effect energization thereof and means, independent of the load" to be lifted, operable following energization of said magnet but subject to a given time delay, to e'fiect automatically 2'. predetermined reduction in-power supplied to said magnet.

2. The combination with a lifting magnet, of means to effect energization of said magnet and means to reducethe power supplied to said magnet following energization thereof, the latter means comprising a self contained relay separate from said magnet hav-;

ing a time element whereby power reduction is delayed for a predeterminedtime.

3. The combination with a lifting magnet, of a resistance and means to connect said magnet in circuit exclusive of said resistance and thereafter to include said resistance in the circuit of said magnet, said means comprising an electro-responsive switch to be energized to exclude said resistance, and a relay to deenergize said switch, said relay having means affording a time element incident to its response to deenergize said switch.

pick-up of a load and thereafter to efi'ect auto- I matically and free from control by said magnet a definite reduction in the power supplied to said magnet while maintaining the latter effective to hold its load, said controller including means affording a predetermined time delay incident to such reduction in power.

6. A lifting magnet controller comprising in combination means to supply the controlled magnet with power for load pick-up and to afl'ord reduction in power supply to the magnet while maintaining the latter effective to hold its load, and meansinsuring a definite and limited time element incident to such reduction in power supply.

- 7. The combination with a lifting magnet, of a resistance, and a controller to complete the circuit of said magnet exclusive of said resistance and thereafter to include said resistance in circuit with said magnet, said controller including means insuring a definite time element incident to inclusion of said resistance to alford said magnet an adequate period in which to pick up its load and said controller including means whereby its operation is rendered independent of the mag netic flux of said magnet.

In witness whereof I affix my signature.

KENNETH YOUNGHUSBAND. 

